ML19143A269

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NRC International Workshop on Age-Related Degradation of Reactor Vessels and Internals - NRC Regulatory Presentation
ML19143A269
Person / Time
Issue date: 05/23/2019
From: Allen Hiser
Division of Materials and License Renewal
To:
Hiser A, 415-5650
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Download: ML19143A269 (30)
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Aging Management and Subsequent License Renewal in the United States Allen Hiser, Jr.

Senior Technical Advisor Division of Materials and License Renewal Office of Nuclear Reactor Regulation NRC International Workshop on Age-Related Degradation of Reactor Vessels and Internals May 23, 2019

OUTLINE

  • Summary 2

WHAT IS AGING MANAGEMENT?

  • Design, fabrication, construction, installation, testing and operation steps to:

- Inhibit or preclude aging degradation (e.g.,

material selection and environmental control)

- Identify degradation conditions in SSCs prior to a loss of intended function

- Ensure effective corrective actions 3

HOW IS AGING MANAGED POST-START UP?

  • First 40 years - Part 50

- Regulation

- NRC actions (orders, etc.)

- Industry voluntary initiative

- Emphasis on safety-related and RCS

- Builds upon aging management activities implemented for first 40 years

- Expands the scope of SSCs covered by aging management 4

FOR FIRST 40 YEARS (1/2)

  • Requirements

- 50.55a: ASME Code inspections

- 50.65: Maintenance rule

- 50.49 (EQ), 50.61 & 61(a) (PTS), Appendix G (fracture toughness requirements), Appendix H (RPV surveillance requirements) . . .

  • NRC actions

- Orders

- Generic Letter

  • GL-16-01, Monitoring of Neutron-Absorbing Materials in Spent Fuels Pools 5

FOR FIRST 40 YEARS (2/2)

  • Industry voluntary initiatives

- Reduces need for NRC to impose requirements

- BWR Vessels and Internals Program

  • Vessel internals cracking, etc.

- Materials Reliability Program

  • Baffle former bolts

- Deviations subject to NRC notification 6

LICENSE RENEWAL RULE - 10 CFR PART 54

  • A limited scope review based on Regulatory Process Essential Elements
  • Rule provisions

- Permits renewal for up to 20 years (e.g., 40 to 60 years)

- Can apply 20 years before license expiration per 54.17(c)

- Must apply at least 5 years before expiration per 2.109(b)

- A renewed license may be subsequently renewed per 54.31(d)

- No restrictions on number of subsequent renewals

  • Focus is on demonstrating adequate management of the effects of aging for long-lived, passive structures and components important to plant safety

- Other aspects of original license are not reconsidered

- A program based solely on detecting structure and component failures is not considered an effective aging management program 7

LICENSE RENEWAL SAFETY PRINCIPLES

  • Plant safety assured by regulatory process

- Same plant operating rules for the renewal term

- The plants current licensing basis (CLB) to be maintained

REGULATORY PROCESS ESSENTIAL ELEMENTS

  • Effective compliance with regulations
  • On-site resident inspectors and specialized inspections
  • Performance assessments of inspection findings
  • Operating experience analysis and utilization
  • Safety issue resolutions (generic and plant specific)
  • Materials aging & degradation issues important to safety addressed by

- Rule changes, generic communications, orders, voluntary actions 9

BASIS FOR RULE

  • Statement of Considerations - 1991 Rule

- 56 Federal Register 64943; December 13, 1991

- Foundation for the Adequacy of the Licensing Bases - A Supplement to the Statement of Considerations for the Rule on Nuclear Power Plant License Renewal (10 CFR Part 54)

- ADAMS Accession No. ML080310668

  • Statement of Considerations - 1995 Rule

- 60 Federal Register 22461; May 8, 1995 10

SCOPE OF LICENSE RENEWAL

  • Safety-related systems, structures, and components (SSCs)

- Maintain integrity of the reactor coolant pressure boundary

- Ensure capability to shut down and maintain safe shutdown

- Prevent or mitigate offsite exposures comparable to 10 CFR Part 100

  • Non-safety related SSCs whose failure could affect safety-related SSC functions
  • SSCs relied upon for compliance with the Commissions regulations for:

- Fire Protection (10 CFR 50.48)

- Environmental qualification (10 CFR 50.49)

- Pressurized thermal shock (10 CFR 50.61)

- Anticipated transients without scram (10 CFR 50.62)

- Station blackout (10 CFR 50.63) 11

SCOPING & SCREENING

  • Process for determining which structures and components require an aging management review (AMR)
  • Scoping - Identify SSCs that are within scope
  • Screening - Include only those structures and components (SCs) that are passive and long-lived
  • Passive = perform an intended function without moving parts or without a change in configuration or properties
  • Long-lived = not subject to replacement based on a qualified life or specified time period
  • Reliability and performance of active structures and components are covered by compliance with the Maintenance Rule (10 CFR 50.65) 12

SAFETY REVIEW

  • Review adequacy of scoping and screening
  • Assess adequacy of aging management review - have all relevant aging effects been identified and will they be effectively managed (using aging management programs)
  • Adequacy of evaluation of time-limited aging analyses (TLAAs)

LICENSE RENEWAL GUIDANCE DOCUMENTS

  • These documents are subject to change using the License Renewal-Interim Staff Guidance (ISG-LR) process 14

GALL-SLR REPORT

- NUREG-2191, issued 2017

- Provides assessments for aging management review, including identification of materials, environments and aging effects that require management

- Identifies acceptable Aging Management Programs (AMPs)

- Defines terms (structures and components, materials, environments, aging effects, significant aging mechanisms) 15

SRP-SLR

- NUREG-2192, issued 2017

- Guidance for NRC staff review of

- Scoping and Screening

- Aging Management Review

- Time-limited Aging Analyses (TLAAs)

- e.g., metal fatigue, reactor pressure vessel (RPV) neutron embrittlement, environmental qualification

- UFSAR supplement description of AMPs

- UFSAR supplement description of TLAAs 16

STANDARDS FOR APPROVAL A renewed license may be issued if the Commission finds that:

- Actions have been identified and have been or will be taken such that there is reasonable assurance that the activities authorized by the renewed license will continue to be conducted in accordance with the CLB. The actions are with respect to

  • managing the effects of aging during the period of extended operation on the functionality of structures and components
  • time-limited aging analyses

- Requirements for Environmental review have been satisfied

- Any consideration of Commission rules and regulations in adjudicatory proceedings has been resolved 17

SUBSEQUENT LICENSE RENEWAL (SLR)

  • Operation from 60 to 80 years
  • Specific regulatory documents have been issued -

GALL-SLR and SRP-SLR

  • Certain issues up to plant-specific resolution
  • Optimization of the review process

- 18 month review (reduced from 22 months)

- Increased use of in-office audits and web portals

- Only final SER issued (previously included an open items SER)

CONCERNS FOR AGING

  • Identification of potential new aging phenomena Known mechanisms New phenomena
  • Approaches for identifying potential aging phenomena Expanded materials degradation assessment Results from 1st renewal aging management programs Domestic and international operating experience Research findings 19

NRC ACTIONS ON SUBSEQUENT RENEWAL

  • Expert panel process to identify potential materials degradation issues for 80 years of operation
  • Audits to assess results from implementation of AMPs at three plants with renewed licenses
  • Public meetings with industry on technical issues, including operating experience and industry research activities
  • NRC staff review of information and propose aging management approaches for 80 years of operation 20

BASIS FOR CHANGES TO DEVELOP GALL-SLR AMPS

  • To reflect expected aging differences for increased operating time from 60 to 80 years
  • New plant operating experience since GALL Rev. 2
  • Gaps identified in current guidance
  • Improvements in efficiency and effectiveness of applications and NRC reviews
  • Corrections to GALL Rev. 2 and SRP-LR Rev. 2
  • Incorporate Interim Staff Guidance since GALL Rev. 2 21

SLR TECHNICAL ISSUES

- Trends for high fluence levels

- Surveillance programs

  • Reactor vessel internals - high fluence effects

- Irradiation-assisted stress corrosion cracking

- Loss of fracture toughness

- Void swelling

  • Concrete and containment performance

- Long-term radiation and high temperature exposure

- Alkali-silica reaction (ASR)

  • Electrical cables

- Environmental qualification

- In-service testing of cables

- Long-term submersion of low and medium voltage cables 22

NEW TOPIC FROM SLR APPLICATIONS

- First SLR applicants have no concrete shielding between the RPV and the support steel

- Low temperature - 150°F

- Copper 0.30 wt-%

- NUREG-1509 analysis 23

Reactor Vessel Material Surveillance AMP PLANT A (1 untested capsule) 9 8 80 years 7

Neutron Fluence (10^19) 6 60 years Tested 5 Untested 60 years 4

80 years 3 60 years 60 years 2

80 years PLANT B 80 years (4 untested capsules) 1 9 80 years 0 8 1960 1980 2000 2020 2040 2060 Neutron Fluence (10^19) 7 Date (plant started 1969) 6 60 years Tested 5 Deferred 4 60 years 3 60 years 80 years 60 years 2

80 years 1 80 years 0

1970 1990 2010 2030 2050 2070 Date (plant started 1972) 24

RESIDUALS FOR WELD MATERIALS 25

RESIDUALS FOR BASE MATERIALS 26

FLUENCE FACTOR RG 1.99, REV. 2 27

LICENSE RENEWAL STATUS 98 operating

  • 33 BWRs 90 units with renewed licenses 49 units in the period of extended operation 28

29 STATUS OF SLR

  • Three SLR applications under review

- Turkey Point, Units 3 and 4 (PWR) - accepted May 2018

- Peach Bottom, Units 2 and 3 (BWR) - accepted September 2018

- Surry, Units 1 and 2 (PWR) - accepted December 2018

- [North Anna, Units 1 and 2 (PWR) - expected 2020]

  • Application subject to acceptance review:

- To determine if there is sufficient technical information in scope and depth to allow the NRC staff to complete its detailed technical review.

- To identify whether the application has any readily apparent information insufficiencies in its characterization of the regulatory requirements or the licensing basis of the plant.

SUMMARY

- Supported by Regulatory Process Essential Elements

  • Licenses have been renewed for over 90% of U.S. plants and reviews of remaining plants (except two) are ongoing or planned
  • Licensees are responsible for demonstrating that aging is adequately managed for licensed operating period
  • NRC ensures that plants will be operated with reasonable assurance of adequate protection of the public health and safety
  • NRC is reviewing SLR applications for 3 sites (6 units) 30
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